Commit dbcdbdfd authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

objtool: Rework instruction -> symbol mapping 



Currently insn->func contains a instruction -> symbol link for
STT_FUNC symbols. A NULL value is assumed to mean STT_NOTYPE.
However, there are also instructions not covered by any symbol at all.
This can happen due to __weak symbols for example.

Since the current scheme cannot differentiate between no symbol and
STT_NOTYPE symbol, change things around. Make insn->sym point to any
symbol type such that !insn->sym means no symbol and add a helper
insn_func() that check the sym->type to retain the old functionality.

This then prepares the way to add code that depends on the distinction
between STT_NOTYPE and no symbol at all.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
parent 08ef8c40

tools/objtool/check.c

+55 −50
Original line number Diff line number Diff line
@@ -62,12 +62,12 @@ static struct instruction *next_insn_same_func(struct objtool_file *file, 
					       struct instruction *insn)

{

	struct instruction *next = list_next_entry(insn, list);

	struct symbol *func = insn->func;

	struct symbol *func = insn_func(insn);



	if (!func)

		return NULL;



	if (&next->list != &file->insn_list && next->func == func)

	if (&next->list != &file->insn_list && insn_func(next) == func)

		return next;



	/* Check if we're already in the subfunction: */
@@ -83,7 +83,7 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file, 
{

	struct instruction *prev = list_prev_entry(insn, list);



	if (&prev->list != &file->insn_list && prev->func == insn->func)

	if (&prev->list != &file->insn_list && insn_func(prev) == insn_func(insn))

		return prev;



	return NULL;
@@ -133,7 +133,7 @@ static bool is_sibling_call(struct instruction *insn) 
	 * sibling call detection consistency between vmlinux.o and individual

	 * objects.

	 */

	if (!insn->func)

	if (!insn_func(insn))

		return false;



	/* An indirect jump is either a sibling call or a jump to a table. */
@@ -207,7 +207,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, 
		return false;



	insn = find_insn(file, func->sec, func->offset);

	if (!insn->func)

	if (!insn_func(insn))

		return false;



	func_for_each_insn(file, func, insn) {
@@ -243,7 +243,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func, 
				return false;

			}



			return __dead_end_function(file, dest->func, recursion+1);

			return __dead_end_function(file, insn_func(dest), recursion+1);

		}

	}
@@ -427,7 +427,10 @@ static int decode_instructions(struct objtool_file *file) 
		}



		list_for_each_entry(func, &sec->symbol_list, list) {

			if (func->type != STT_FUNC || func->alias != func)

			if (func->type != STT_NOTYPE && func->type != STT_FUNC)

				continue;



			if (func->return_thunk || func->alias != func)

				continue;



			if (!find_insn(file, sec, func->offset)) {
@@ -437,9 +440,11 @@ static int decode_instructions(struct objtool_file *file) 
			}



			sym_for_each_insn(file, func, insn) {

				insn->func = func;

				if (insn->type == INSN_ENDBR && list_empty(&insn->call_node)) {

					if (insn->offset == insn->func->offset) {

				insn->sym = func;

				if (func->type == STT_FUNC &&

				    insn->type == INSN_ENDBR &&

				    list_empty(&insn->call_node)) {

					if (insn->offset == func->offset) {

						list_add_tail(&insn->call_node, &file->endbr_list);

						file->nr_endbr++;

					} else {
@@ -1397,19 +1402,19 @@ static void add_return_call(struct objtool_file *file, struct instruction *insn, 


static bool same_function(struct instruction *insn1, struct instruction *insn2)

{

	return insn1->func->pfunc == insn2->func->pfunc;

	return insn_func(insn1)->pfunc == insn_func(insn2)->pfunc;

}



static bool is_first_func_insn(struct objtool_file *file, struct instruction *insn)

{

	if (insn->offset == insn->func->offset)

	if (insn->offset == insn_func(insn)->offset)

		return true;



	if (opts.ibt) {

		struct instruction *prev = prev_insn_same_sym(file, insn);



		if (prev && prev->type == INSN_ENDBR &&

		    insn->offset == insn->func->offset + prev->len)

		    insn->offset == insn_func(insn)->offset + prev->len)

			return true;

	}
@@ -1450,7 +1455,7 @@ static int add_jump_destinations(struct objtool_file *file) 
		} else if (reloc->sym->return_thunk) {

			add_return_call(file, insn, true);

			continue;

		} else if (insn->func) {

		} else if (insn_func(insn)) {

			/*

			 * External sibling call or internal sibling call with

			 * STT_FUNC reloc.
@@ -1492,8 +1497,8 @@ static int add_jump_destinations(struct objtool_file *file) 
		/*

		 * Cross-function jump.

		 */

		if (insn->func && jump_dest->func &&

		    insn->func != jump_dest->func) {

		if (insn_func(insn) && insn_func(jump_dest) &&

		    insn_func(insn) != insn_func(jump_dest)) {



			/*

			 * For GCC 8+, create parent/child links for any cold
@@ -1510,10 +1515,10 @@ static int add_jump_destinations(struct objtool_file *file) 
			 * case where the parent function's only reference to a

			 * subfunction is through a jump table.

			 */

			if (!strstr(insn->func->name, ".cold") &&

			    strstr(jump_dest->func->name, ".cold")) {

				insn->func->cfunc = jump_dest->func;

				jump_dest->func->pfunc = insn->func;

			if (!strstr(insn_func(insn)->name, ".cold") &&

			    strstr(insn_func(jump_dest)->name, ".cold")) {

				insn_func(insn)->cfunc = insn_func(jump_dest);

				insn_func(jump_dest)->pfunc = insn_func(insn);



			} else if (!same_function(insn, jump_dest) &&

				   is_first_func_insn(file, jump_dest)) {
@@ -1521,7 +1526,7 @@ static int add_jump_destinations(struct objtool_file *file) 
				 * Internal sibling call without reloc or with

				 * STT_SECTION reloc.

				 */

				add_call_dest(file, insn, jump_dest->func, true);

				add_call_dest(file, insn, insn_func(jump_dest), true);

				continue;

			}

		}
@@ -1572,7 +1577,7 @@ static int add_call_destinations(struct objtool_file *file) 
				return -1;

			}



			if (insn->func && insn->call_dest->type != STT_FUNC) {

			if (insn_func(insn) && insn->call_dest->type != STT_FUNC) {

				WARN_FUNC("unsupported call to non-function",

					  insn->sec, insn->offset);

				return -1;
@@ -1668,7 +1673,7 @@ static int handle_group_alt(struct objtool_file *file, 
		nop->offset = special_alt->new_off + special_alt->new_len;

		nop->len = special_alt->orig_len - special_alt->new_len;

		nop->type = INSN_NOP;

		nop->func = orig_insn->func;

		nop->sym = orig_insn->sym;

		nop->alt_group = new_alt_group;

		nop->ignore = orig_insn->ignore_alts;

	}
@@ -1688,7 +1693,7 @@ static int handle_group_alt(struct objtool_file *file, 
		last_new_insn = insn;



		insn->ignore = orig_insn->ignore_alts;

		insn->func = orig_insn->func;

		insn->sym = orig_insn->sym;

		insn->alt_group = new_alt_group;



		/*
@@ -1882,7 +1887,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn, 
	struct reloc *reloc = table;

	struct instruction *dest_insn;

	struct alternative *alt;

	struct symbol *pfunc = insn->func->pfunc;

	struct symbol *pfunc = insn_func(insn)->pfunc;

	unsigned int prev_offset = 0;



	/*
@@ -1909,7 +1914,7 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn, 
			break;



		/* Make sure the destination is in the same function: */

		if (!dest_insn->func || dest_insn->func->pfunc != pfunc)

		if (!insn_func(dest_insn) || insn_func(dest_insn)->pfunc != pfunc)

			break;



		alt = malloc(sizeof(*alt));
@@ -1949,7 +1954,7 @@ static struct reloc *find_jump_table(struct objtool_file *file, 
	 * it.

	 */

	for (;

	     insn && insn->func && insn->func->pfunc == func;

	     insn && insn_func(insn) && insn_func(insn)->pfunc == func;

	     insn = insn->first_jump_src ?: prev_insn_same_sym(file, insn)) {



		if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
@@ -1966,7 +1971,7 @@ static struct reloc *find_jump_table(struct objtool_file *file, 
		if (!table_reloc)

			continue;

		dest_insn = find_insn(file, table_reloc->sym->sec, table_reloc->addend);

		if (!dest_insn || !dest_insn->func || dest_insn->func->pfunc != func)

		if (!dest_insn || !insn_func(dest_insn) || insn_func(dest_insn)->pfunc != func)

			continue;



		return table_reloc;
@@ -2415,6 +2420,13 @@ static int decode_sections(struct objtool_file *file) 
	if (ret)

		return ret;



	/*

	 * Must be before add_{jump_call}_destination.

	 */

	ret = classify_symbols(file);

	if (ret)

		return ret;



	ret = decode_instructions(file);

	if (ret)

		return ret;
@@ -2433,13 +2445,6 @@ static int decode_sections(struct objtool_file *file) 
	if (ret)

		return ret;



	/*

	 * Must be before add_{jump_call}_destination.

	 */

	ret = classify_symbols(file);

	if (ret)

		return ret;



	/*

	 * Must be before add_jump_destinations(), which depends on 'func'

	 * being set for alternatives, to enable proper sibling call detection.
@@ -2648,7 +2653,7 @@ static int update_cfi_state(struct instruction *insn, 


	/* stack operations don't make sense with an undefined CFA */

	if (cfa->base == CFI_UNDEFINED) {

		if (insn->func) {

		if (insn_func(insn)) {

			WARN_FUNC("undefined stack state", insn->sec, insn->offset);

			return -1;

		}
@@ -2994,7 +2999,7 @@ static int update_cfi_state(struct instruction *insn, 
		}



		/* detect when asm code uses rbp as a scratch register */

		if (opts.stackval && insn->func && op->src.reg == CFI_BP &&

		if (opts.stackval && insn_func(insn) && op->src.reg == CFI_BP &&

		    cfa->base != CFI_BP)

			cfi->bp_scratch = true;

		break;
@@ -3390,13 +3395,13 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, 
	while (1) {

		next_insn = next_insn_to_validate(file, insn);



		if (func && insn->func && func != insn->func->pfunc) {

		if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {

			/* Ignore KCFI type preambles, which always fall through */

			if (!strncmp(func->name, "__cfi_", 6))

				return 0;



			WARN("%s() falls through to next function %s()",

			     func->name, insn->func->name);

			     func->name, insn_func(insn)->name);

			return 1;

		}
@@ -3638,7 +3643,7 @@ static int validate_unwind_hints(struct objtool_file *file, struct section *sec) 


	while (&insn->list != &file->insn_list && (!sec || insn->sec == sec)) {

		if (insn->hint && !insn->visited && !insn->ignore) {

			ret = validate_branch(file, insn->func, insn, state);

			ret = validate_branch(file, insn_func(insn), insn, state);

			if (ret && opts.backtrace)

				BT_FUNC("<=== (hint)", insn);

			warnings += ret;
@@ -3861,7 +3866,7 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio 
	 * In this case we'll find a piece of code (whole function) that is not

	 * covered by a !section symbol. Ignore them.

	 */

	if (opts.link && !insn->func) {

	if (opts.link && !insn_func(insn)) {

		int size = find_symbol_hole_containing(insn->sec, insn->offset);

		unsigned long end = insn->offset + size;
@@ -3885,10 +3890,10 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio 
			/*

			 * If this hole jumps to a .cold function, mark it ignore too.

			 */

			if (insn->jump_dest && insn->jump_dest->func &&

			    strstr(insn->jump_dest->func->name, ".cold")) {

			if (insn->jump_dest && insn_func(insn->jump_dest) &&

			    strstr(insn_func(insn->jump_dest)->name, ".cold")) {

				struct instruction *dest = insn->jump_dest;

				func_for_each_insn(file, dest->func, dest)

				func_for_each_insn(file, insn_func(dest), dest)

					dest->ignore = true;

			}

		}
@@ -3896,10 +3901,10 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio 
		return false;

	}



	if (!insn->func)

	if (!insn_func(insn))

		return false;



	if (insn->func->static_call_tramp)

	if (insn_func(insn)->static_call_tramp)

		return true;



	/*
@@ -3930,7 +3935,7 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio 


		if (insn->type == INSN_JUMP_UNCONDITIONAL) {

			if (insn->jump_dest &&

			    insn->jump_dest->func == insn->func) {

			    insn_func(insn->jump_dest) == insn_func(insn)) {

				insn = insn->jump_dest;

				continue;

			}
@@ -3938,7 +3943,7 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio 
			break;

		}



		if (insn->offset + insn->len >= insn->func->offset + insn->func->len)

		if (insn->offset + insn->len >= insn_func(insn)->offset + insn_func(insn)->len)

			break;



		insn = list_next_entry(insn, list);
@@ -3967,7 +3972,7 @@ static int validate_symbol(struct objtool_file *file, struct section *sec, 


	state->uaccess = sym->uaccess_safe;



	ret = validate_branch(file, insn->func, insn, *state);

	ret = validate_branch(file, insn_func(insn), insn, *state);

	if (ret && opts.backtrace)

		BT_FUNC("<=== (sym)", insn);

	return ret;
@@ -4104,7 +4109,7 @@ static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn 
			continue;

		}



		if (dest->func && dest->func == insn->func) {

		if (insn_func(dest) && insn_func(dest) == insn_func(insn)) {

			/*

			 * Anything from->to self is either _THIS_IP_ or

			 * IRET-to-self.

tools/objtool/include/objtool/check.h

+11 −1
Original line number Diff line number Diff line
@@ -67,11 +67,21 @@ struct instruction { 
	struct reloc *jump_table;

	struct reloc *reloc;

	struct list_head alts;

	struct symbol *func;

	struct symbol *sym;

	struct list_head stack_ops;

	struct cfi_state *cfi;

};



static inline struct symbol *insn_func(struct instruction *insn)

{

	struct symbol *sym = insn->sym;



	if (sym && sym->type != STT_FUNC)

		sym = NULL;



	return sym;

}



#define VISITED_BRANCH		0x01

#define VISITED_BRANCH_UACCESS	0x02

#define VISITED_BRANCH_MASK	0x03